Re: repeated measures models
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: repeated measures models




> 
> Arthur wrote:-
> 
> <snip>
> >Lets start with 
> > 
> >  intake1 intake2 intake3 other ~ Trait Tr.line Tr.feedflock Tr.damage,
> >  Tr.brtype Tr.sex !r Tr.sire
> > 
> > 1 2 0 
> > 1728   #no. of animals in the data
> > Tr 0 US  E11 E12 E22 E31 E32 E33 E41 E42 E43 E44  !=1212213330
> > 
> > Tr.sire 2
> > Tr 0 US  G11 G12 G22 G31 G32 G33 G41 G42 G43 G44  !=4545546660
> > sire
> >
> >SO what we have here is setting the model up as standard multivariate
> >and then constraining the intake variances and covariances.
> >
> >You could of course fit it with unconstrained variances.
> >
> >The way the first model was fitted, the 'units' term gave the E12 E32 R32
> >covariances and the  'units + residual' gave the E11, E22 and E33 terms.
> >
> >The sire term gave G11=G21=G22=G31=G32=G33
> >
> >When you get this running, you may see how to extend to more complex models.
> 

Ron wrote

> Okay, I can see how that might work.
> 
> But for a repeatability model, you need to have the
> genetic correlation equal to one among the 3 intake
> traits. I don't see how you do this, I know it
> uses the and() function in some way, but I don't understand it.
> 
> Ron.

Arthur replies:
I'm not convinced you need to have a genetic correlation of 1 but
if you do, and want to fit the model, the way would be to fit
an equivalent model:

      ...      !r sire Tr|4/sire ... 
      
      
      sire 2
      2 0 US S11 S21 S22
      sire
      
  
  Under this model, the genetic variance for intake  is S11
                                         for other   is S11 + S22
                              covariance is             S11+S21  \
                                
  For computational ease, you might like to scale the  unrepeated trait
  so that its sire variance is greater than the sire variance for intake
  [so that S22 has a positive value]

Arthur  
> 

<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Arthur Gilmour PhD                    email: Arthur.Gilmour@agric.nsw.gov.au
Senior Research Scientist (Biometrics)                 fax: <61> 2 6391 3899
NSW Agriculture                             telephone work: <61> 2 6391 3815
Orange Agricultural Institute                         home: <61> 2 6362 0046
Forest Rd, ORANGE, 2800, AUSTRALIA         

ASREML is currently free by anonymous ftp from pub/aar on ftp.res.bbsrc.ac.uk
    Point your web browser at ftp://ftp.res.bbsrc.ac.uk/pub/aar/ 
    in the IACR-Rothamsted information system  http://www.res.bbsrc.ac.uk/ 

To join the asreml discussion list, send the message  
     subscribe
to  asreml-request@chiswick.anprod.CSIRO.au

The address for messages to the list is asreml@chiswick.anprod.CSIRO.au

                        <> <> <> <> <> <> <>
"Blessed are the pure in heart for they shall see God"  Jesus; Matthew 5:8
<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>